<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <script src="../js/vue.js"></script>
</head>

<body>
  <div id="root">
    姓：<input type="text" v-model="firstName"><br>
    名：<input type="text" v-model="lastName"><br>
    全名：<span>{{firstName}}-{{lastName}}</span>
  </div>
  <script>
    Vue.config.productionTip = false
    const vm = new Vue({
      el: '#root',
      data: {
        firstName: '张',
        lastName: '三'
      }
    })
  </script>
</body>

</html>